The present invention relates to compressors that may be applied to, for example, automotive air-conditioning systems. More particularly, the present invention pertains to mechanisms for separating and recovering lubricating oil from refrigerant gas in compressors.
Japanese Unexamined Patent Publication No. 5-240158 and Japanese Unexamined Patent Publication No. 8-35485 describe compressors that incorporate oil recovery devices. Each of these compressors has a housing, which houses a discharge chamber, a crank chamber, and cylinder bores. A rotatable drive shaft is supported in the housing such that it extends through the crank chamber. A swash plate is supported in the crank chamber and supported by the drive shaft such that it rotates integrally with the drive shaft. A piston is accommodated in each cylinder bore and coupled to the swash plate. When the drive shaft is rotated by an external drive source, such as an automotive engine, the swash plate converts the rotation of the drive shaft to linear reciprocation of each piston in the associated cylinder bore. The reciprocation of each piston draws refrigerant gas into the cylinder bore, compresses the gas, and discharges the gas into the discharge chamber.
A typical compressor has a muffler located downstream of the discharge chamber. The muffler has a gas outlet that is connected with an external refrigerant circuit. Accordingly, the refrigerant gas in the discharge chamber is sent to the external refrigerant circuit by way of the muffler. The muffler attenuates the pressure pulsation of the refrigerant gas. This reduces vibrations and noise, which result from pressure pulsation of the refrigerant gas.
Atomized lubricating oil is suspended in the refrigerant gas to lubricate moving parts in the compressor as the refrigerant gas flows through the compressor. However, the lubricating oil that travels through the compressor is sent to the external refrigerant circuit together with the refrigerant gas. If a large amount of lubricating oil is discharged from the compressor, the amount of lubricating oil in the compressor decreases. This may lead to insufficient lubrication. Accordingly, the mufflers of the compressors described in the above publications incorporate a device for separating and recovering the lubricating oil from the refrigerant gas. The oil recovery device includes an oil separating chamber, which is arranged in the muffler, and a cylindrical tube, which is secured to the gas outlet such that the tube projects into the oil separating compartment. Further, a recovery passage connects the oil separating chamber to the crank chamber.
As the refrigerant gas flows from the muffler toward the external refrigerant circuit, the refrigerant gas swirls about the tube in the oil separating chamber. The refrigerant gas then enters the tube and flows through the gas outlet into the external refrigerant circuit. Centrifugal force acts on the refrigerant gas swirling about the tube. The centrifugal force separates the lubricating oil from the refrigerant gas. The separated lubricating oil is then sent to the crank chamber through the recovery passage. This maintains satisfactory lubrication in the compressor.
The location of the gas outlet is normally changed in accordance with the type of vehicle in which the compressor is installed. The layout of various equipment in the engine compartment differs in each type of vehicle. Thus, the arrangement of the compressor and the external refrigerant circuit depends on the spatial limitations resulting from the layout of the engine compartment. There are cases in which the location of the gas outlet on the compressor must be changed because of the engine compartment layout. As a result, the structure of the oil recovery device must also be changed. Such changes decrease production efficiency and increases costs.